Influence of yttrium doping on the nonlinear optical limiting properties of cadmium molybdate nanostructures

The emerging demand for the production of nonlinear optical materials with high optical limiting performance has an apparent impact in the field of nonlinear optics owing to their wide application in photonic devices. In this regard, transition metal molybdates have received attention owing to their remarkable optical and luminescence characteristics, leading to their extensive use in next generation optoelectronics devices. Herein, we report the nonlinear optical response of yttrium (Y³⁺) doped cadmium molybdate (CdMoO₄) nanostructures synthesized via a co-precipitation technique. The X-ray diffraction and Raman spectroscopy results confirm the formation of CdMoO₄ nanostructures with a tetragonal structure having the I4₁/a space group. High resolution scanning electron microscopy (HRSEM) of the pristine CdMoO₄ exposed the cubic flat edged nature of the nanostructures and that doping results in particle size reduction due to lattice contraction. X-ray photo electron spectroscopy confirmed the chemical state of the elements present in Y³⁺doped CdMoO₄. The optical properties of the samples were studied using UV-Vis Spectroscopy and the bandgap was found to increase upon Y³⁺ doping. The NLO response measured using the open aperture z-scan technique with a Nd: YAG pulsed laser (532 nm, 7 ns, 10 Hz) exhibited a reverse saturable absorption arising from a two photon absorption (2PA) process. An increase in the 2PA coefficient and simultaneous decrease in the onset of the optical limiting threshold clearly suggests the great potential of the yttrium-doped CdMoO₄ nanoparticles for good optical limiting applications.